Two-stroke internal-combustion engine



F. P. FLINT. TWO-STROKE INTERNAL COMBUSTION ENGINE.

' APPLICATION FILED IIINE 3, I9I9.

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F. P. FLINT. TWOLSTROKE INTERNAL COMBUSTIONENGINE.

APPLICATION FILED JUNE 3, |919- Patented June 1, 1920.

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FREDERICK PEECY ELINT, 0E PoNDERs END, ENGLAND.

TWO-STROKE INTERNAL-COMBUSTION ENGINE;

Application filed June 3, 1919'.

To allwtom t may concern:

Be it known that I, FREDERICK PERCY FEINT, a subject of the King of England2 residing at Penders: End, in the' county of lViddleseX,y England, have invented certainnew and l useful Improvements in Two- Stroke Internal-Combustion Engines, of which the following is a specification.

This invention relates to two-stroke cycle internal-'combustion engines having a working-cylinder and a co-aXial compressioncyllin'der for the charge', and has forits primary object to improve the` construction 1n detaily of such engines, particularly with a viewV to securing 'simplicity and cheapness intheir construction,- but alsoV with a View to their satisfactory operation,` especially as regards the admission of the charge' to the working cylinder;

To thisI end, the invention consists in the constructiom arrangement and combination of parts described hereinafter and pointed out in the claims. i V

One embodiment of the invention and a modification thereof are diagrammatically illustrated by way of example inthe accompanying drawing, wherein' Figure 1l is a vertical sectional elevation showing one formf of two-stroke cycle internal-combustion engi-ne according to the invention, and f Fig. '2 is a detail/viewl in vertical section showing a mo'diiied form of passage connecting the admission valve with the working-cylinder.

Like reference characters designate like parts in .both the views.

Referring first to l, the engine comprises a two-diameter cylinder-casting A seourely mounted o n a crank-case B in which is journaled a crank-shaft G which is connected by a connecting r'o'd D t'o the gudgeon-pi-n E of a duplex piston F.

The cylinder-casting' is made in one piece, having at what will be termed the upper end,l a worldng-cylinder A1, and at the end adjacent the crank-case B a compression-cylinder A2 co-aXial with and of larger diameter than the former. A duct A3 is formed in the casting with its length running parallel/to the cylinder axis and opening radially inward at its bottom end through a right-angled b'end int'o what is geometrically, though not practically, the cavity of the w'o'rking-cylnder.v The-upper Specification of Letters Patent.

rasant-ed June i, 1920.

Serial.' No. 301,505.

end of this duct opens into a cavity forming an inlet-valve pocket A4 from which communication Ais givento the headv of the working-cylinder through a lateral port A5. An inlet-valve G isv arranged with its major axis parallel to the cylinder axis, a guideway AG for its spindle Gr14 being located parallel with, and at a short radial distance from, the duct A3, At its/upper end the duct A3 opens into the pocket -A4 containing a seating A7 for the valve Gr. The lower end of the duct A3 opens radially outward through an outlet which is normally closed by a screw-plug H. As the guideway A6 opens into'` the lower end of the duct A3 at thisoutlet, the removal of the plug I-I not only 'gives access to` the duct for clean-ing purposes,` but also enables a return spring G2 of the inlet-valve to be adjusted by means of a ring G3 screwed on the lower end of the spindle G1, This'valve is conveniently auto'- matic, but, if preferred, it may be operated mechanically.

An admission-valve J forv the combustible mixture is seated inthe flange-like formation occurring at A8 where the workingcylinder A1 merges into the compressioncylinder A2, the said flange-like formation being due to the change in diameter vin the cylinder-casting A. This admission-valve J is a suction-valve controlled by a spring J1.

The piston. F is constructed as a duplex or differential piston of two diameters, the

upper working-piston F1 corresponding with' the working-cylinder and the lower compression-piston F2 with the compressioncylinder. The construction is such that the piston F2 is of short axial length compared with the piston F1 and thus has the appearance of being an axial extension of a llange upon the latter. Both pistons are provided with grooves for rings, and' in the body or trunk of the working-piston F1 a cavity or recessv F 3 is formed just above the upper face of the compression-piston F2'. This cavity is so;` situated as to register with the open lnwardly-dir'ected end of the aforesaid right-angled bend of the duct A3, the registering position being, as will be obvious, that when the working-piston- F1 is most fully advanced into andy inclosed by its cylinder...

The crank-case B is secured by means not shown in the drawing to the lower open end of the compression-cylinder A2 itrcontains the balanced cran-k constituting" a flywheel,

and, to one side of the latter', an exhaustvalve operating cam K keyed on the shaft C. The crank-case is divided into two halves at B1 in a plane containing the lane of oscillation of the connecting-rod and in the half on the same side as theL cam K is an oil-pump shown at L. This pump comprises a' cylinder B2 formed integral with the crank-case, and a spring-controlled plunger L1 which is operated by direct engagement with the cam K. The lower end of the plunger is hollow and is fitted at its lower end with a non-returnvalve L2 so as to form a bucket A similar `non-return valve L3 is fitted in the bottom of the pump cylinder B1 and controls a duct opening into the bottomy of the crank-case, through which oil flows to the pump. "When the pump is operated, the oil is delivered by way of a port in the plunger midway along its length to an outlet B3 in the crank-case, this outlet being connected by conduits, not shown, to the parts of the engine requiring lubrication.

l A spring-controlled exhaust-valve M controlling an exhaust-passage M1 in the wall of the cylinder A1 is provided diametrically opposite the inlet-valve Gr, but has its'seating A9 farther away, measured along the aXis of the engine, from the axisy of the crank-shaft than is the inlet-valve. The spindle M2 of the exhaust-valve is guided in a long guide N mounted in the wall `of the exhaust way M1 and is guided through the medium of an intermediate rod O by the tappet P. The intermediate rod O slides in lugs cast on the cylinder-casting, and the tappet P is housed in a bearing P1 in the crank-case B and is operated by the cam K.

In addition to the exhaust-valve M a lateral exhaust-port 'A10 is provided in the cylinder wall so as to be covered and uncovered by the piston F1 in the well-known manner. l

An internally threaded bushing Q is provided, as usual, in the head of the cylinder A1 for the reception of a sparking plug. Threaded caps R and R1.are also provided in apertures in the ycylinder casting to give access to the inlet-valve G and the exhaustvalve M, respectively.

In the modifiedy construction ,shown 'in Fig. 2, an annularpocket A11, not however -formed as a complete ring, is formed in the upper portionof the wall of the workingcylinder A1vand is connected with an ami-- iliary supply duct A12 which is controlled at. its one endy by a second-inlet-valve G1 and is connected at its other end to the duct A.

The subsidiary pocket A11 opens into the: working-cylinder A1 by way of ports A11.. These ports are situated farther inward in the direction of the stroke of the enginethan is the port A*s controlled by the valve G. Owing to the described position. of these ports A13 they are covered and uncovered by the piston F1 sooner and later, respectively, than is the port A5, vwhen the piston moves inward and outward in the cylinder A1. lThe subsidiary pocket therefore serves to aiford a kind of reservoir of combustible mixture, its object being to increase'the supply of fuel to the working-cylinder during the expansion stroke as compared with the amount thatcan be delivered to it at the commencement of the expansion stroke by the ordinary means. v i

The volume of the compression-cylinder A2 swept out by its piston F2 is so dimensioned as to take account not only of the volume of the working-cylinder A1 and its piston F1, but also ofthe duct A3 and, in the event of a subsidiary pocket A11 being provided, of the duct A12, but the volume swept out in the compression-cylinder is obviously so chosen as to give the required ultimate compression in the working-cylinder.

It will be appreciated that the cavity F3 and the cooperating duct A3 are simply to construct and provide, since both may be formed directly in the body yand its respective part in the process of casting the part. Moreover the masking of the inlet port by the piston in the working-cylinder a'ords a simple additional safeguard to prevent ignition being communicated to the charge in the compression-cylinder.

What I claim as my invention and desire to secure by Letters Patent is z- -l. In a two-stroke cycle internal-combustion engine of the character described, the combination of a two-diameter cylinder comprising a working-cylinder having aneX- haust port, and a compression-cylinder which is co-aXial with the working-cylinder and has an admission port, aduplexpiston comprising a working-piston movable `in the said working-cylinder and a compressionpiston movable in the said compression-cylinder, the4 wall of the working-cylinder being provided with a fuel-supply duct whereof its supply end opens into the end of the working-cylinder adjacent to the compression-cylinder and is normally closed by the said working-piston, and whereof its delivery end opens through an inlet port into the end of the working-cylinder remote from the compression-'cylinder and a valve arranged to control the delivery end ,of said duct, the trunk of said working-piston being provided with a cavity so arranged as to periodically establish communication between .the supply end of the saidl duct and thecompression-cylinder when the duplex piston is reciprocated, the said inlet port and the exhaust port of the working-cylinder being located on opposite sides of the workingcylinder `and so situated in the axial-direction thereof that whenthe working-piston is near the end of its instroke, the said inlet port is covered by the working-piston, but the exhaust port is never thus covered, for the purpose specified.

2. In a two-stroke cycle internal-combustion engine of the character described, the combination of a two-diameter cylinder comprising a working-cylinder having an eX- haust port and a compression-cylinder which is co-axial with the working-cylinder and has an admission-port, a duplex piston cornprising a working-piston movable in the said workingcylinder and a compression-piston movable in the said compression-cylinder, the wall of the working-cylinder being provided with a 'fuel-supply duct whereof its supply end opens into the end of the working-cylinder adjacent to the compression-cylinder and is normally closed by the said working-piston, and whereof its delivery end opens into the end of the working-cylinder remote from the compression-cylinder, a

valve arranged to control the delivery end of said duct, the Wall of the working-cylinder being also provided with a pocket which is connected by an auxiliary duct with the uelsupply duct and kopens into the working-cylinder by way of ports which are situated between the delivery end of the said fuel-supply duct and the end of the Working-cylinder adjacent to the compressioncylinder, and a valve arranged to control the communication between said pocket and said auxiliary duct, the trunk of said workingpiston being provided with a cavity so ar# FREDERICK PERC'Y FLINT. 

